In engines for aircraft such as helicopters, it is often necessary to discharge different types of liquids, for example fuel or oil, to prevent the liquids from building up and disrupting the functioning of the engines. For example, some engines require purging operations, which cause losses of liquids (fuel, oil, etc.) that have to be recovered and treated.
In the current state of the art, a return tank is provided for recovering the liquids, i.e. at least one duct is provided to convey the liquids to the aircraft fuel tank. However, this technology has several drawbacks. Indeed, the aircraft manufacturer is forced to provide the return tank used for recovering the different liquids drained from the engine. This technical constraint is exacerbated by the fact that the flow rates and temperatures of the liquids may be high. Leaks can also result from “latent” faults. Moreover, the recovered oil contaminates the fuel stored in the tank. Having to deal with these potential leaks thus places great restrictions on the aircraft manufacturer and does not help the incorporation of the engine on aircrafts that do not have a return tank.
In addition, oil or fuel leaks can occur in the engine as a result of some parts having a faulty seal, yet this may not actually affect the functioning of the parts. In the current state of the art, a maintenance operation is carried out immediately after detection of leaks of this type, which have no adverse effect on the engine, and this increases the frequency of these operations and the overall maintenance costs for an aircraft engine. This is the case in particular in HMU hydromechanical systems, the dynamic seal of which can produce external leaks. The fuel leaks in the region of the drain of the drive are the main reason for pump units/HMUs being removed, even though the leaks do not have a significant impact on the functioning of the engine. It would thus be desirable to be able to keep an HMU hydromechanical system in operation, even if the dynamic seal thereof is not perfect.
Several solutions are known for discharging the liquids drained from an aircraft engine, yet none of these effectively and fully addresses the problem and requirements set out above. For example, one solution is to discharge the drained liquids to a scupper of the engine deck. This solution is unsatisfactory because it leads to liquids being dumped into the atmosphere or onto the runway, which is tolerated less and less. Another solution is to provide the engine with a treatment device for the drain of the liquids, the device comprising a collector designed to collect the liquids drained from the engine. This collector can be connected to the exhaust nozzle of the engine by means of a duct in such a way that the drained liquids are conveyed and pumped from the collector to the jet nozzle where they are combusted. In this case, flames and smoke may appear at the outlet of the jet nozzle, and this is not pleasant to see, in particular when the engine is started up.
The object of the present disclosure is to find a solution to the problem and requirements set out above.